This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Conventional T1 and T2 imaging techniques are useful for observing late structural morphological changes to the cartilage within the femoral-tibial joint but are insensitive to early biochemical changes. T1p weighted imaging has shown promise as a diagnostic measure of early osteoarthritis. T1p relaxation time constant is sensitivity to the interaction between bulk water molecules and extracellular matrix macromolecules such as the proteoglycans in articular cartilage. In this study, we evaluate the efficacy of T1p MRI to characterize osteoarthritis changes in an animal model (Dunkin-Hartley guinea pig) of spontaneous osteoarthritis formation. Future studies may allow T1p MRI to evaluate efficacy of potential therapies for OA.